CVE-2020-28840 – CVE-2020-28840 is a buffer overflow vulnerabili... (How to Fix)

Q: What is the severity of CVE-2020-28840?

CVE-2020-28840 has a CVSS score of 7.8 (HIGH). CVE-2020-28840 is a buffer overflow vulnerability in jhead's jpgfile.c that allows local attackers to execute arbitrary code or cause denial of service. This affects users of jhead version 3.04 who process untrusted JPEG files. The vulnerability stems from improper bounds checking when handling JPEG metadata.

📋 TL;DR

CVE-2020-28840 is a buffer overflow vulnerability in jhead's jpgfile.c that allows local attackers to execute arbitrary code or cause denial of service. This affects users of jhead version 3.04 who process untrusted JPEG files. The vulnerability stems from improper bounds checking when handling JPEG metadata.

💻 Affected Systems

Products:

jhead

Versions: Version 3.04 specifically

Operating Systems: Linux, Windows, macOS, BSD - any OS running jhead

Default Config Vulnerable: ⚠️ Yes

Notes: Only vulnerable when processing JPEG files. Systems using jhead for automated image processing are at higher risk.

📦 What is this software?

Jhead by Matthiaswandel

View all CVEs affecting Jhead →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Local privilege escalation leading to full system compromise via arbitrary code execution as the user running jhead.

🟠

Likely Case

Denial of service (application crash) when processing malicious JPEG files, potentially disrupting workflows.

🟢

If Mitigated

Limited to application crash if exploit fails or is detected by security controls.

🌐 Internet-Facing: LOW - jhead is typically used locally for image processing, not as an internet-facing service.

🏢 Internal Only: MEDIUM - Risk exists for users processing untrusted JPEG files locally, but requires user interaction.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: LOW

Exploitation requires local access and user interaction to process a malicious JPEG file. Proof-of-concept code is available in public advisories.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Fixed in commit 4827ed31c226dc5ed93603bd649e0e387a1778da and later versions

Vendor Advisory: https://github.com/Matthias-Wandel/jhead/security/advisories/GHSA-xh27-xwgj-gqw2

Restart Required: No

Instructions:

1. Update jhead to version after commit 4827ed31c226dc5ed93603bd649e0e387a1778da. 2. For Linux systems: Use package manager (apt/yum) to update jhead package. 3. For manual install: Download latest source from GitHub and recompile.

🔧 Temporary Workarounds

Restrict jhead usage

linux

Limit jhead execution to trusted users and processes only

chmod 750 /usr/bin/jhead
setfacl -m u:trusteduser:rx /usr/bin/jhead

Sandbox execution

all

Run jhead in a container or sandbox when processing untrusted files

docker run --rm -v $(pwd):/data alpine/jhead:latest [options]

🧯 If You Can't Patch

Remove jhead from systems where it's not essential
Implement strict file validation before processing JPEGs with jhead

🔍 How to Verify

Check if Vulnerable:

Check jhead version: jhead -V. If output shows '3.04' or commit before 4827ed31c226dc5ed93603bd649e0e387a1778da, system is vulnerable.

Check Version:

jhead -V 2>&1 | head -1

Verify Fix Applied:

After update, run jhead -V and confirm version is newer than 3.04 or commit includes 4827ed31c226dc5ed93603bd649e0e387a1778da.

📡 Detection & Monitoring

Log Indicators:

Segmentation fault or crash logs from jhead process
Unexpected process termination of jhead

Network Indicators:

Not applicable - local vulnerability

SIEM Query:

Process:jhead AND (EventID:1000 OR Signal:SIGSEGV)

📊 Metadata

CVE ID: CVE-2020-28840

CVSS v3 Score: 7.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-120

Published: August 11, 2023

Last Updated: November 21, 2024

🔗 References

https://bugs.launchpad.net/ubuntu/+source/jhead/+bug/1900820 Exploit,Issue Tracking
https://github.com/F-ZhaoYang/jhead/security/advisories/GHSA-xh27-xwgj-gqw2 Exploit
https://github.com/Matthias-Wandel/jhead/commit/4827ed31c226dc5ed93603bd649e0e387a1778da Patch
https://github.com/Matthias-Wandel/jhead/issues/8 Exploit,Issue Tracking,Patch
https://bugs.launchpad.net/ubuntu/+source/jhead/+bug/1900820 Exploit,Issue Tracking
https://github.com/F-ZhaoYang/jhead/security/advisories/GHSA-xh27-xwgj-gqw2 Exploit
https://github.com/Matthias-Wandel/jhead/commit/4827ed31c226dc5ed93603bd649e0e387a1778da Patch
https://github.com/Matthias-Wandel/jhead/issues/8 Exploit,Issue Tracking,Patch

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2020-28840, you might also want to check these: